The present invention relates to amphibious vehicles, and particularly to hull fairings for recesses in the hull.
In our co-pending Patent Application No. PCT/GB/04/002156, a planing amphibious vehicle hull is shown with recesses in the areas where retractable wheels and their suspensions move during suspension retraction and protraction. Because the suspensions are assembled from below during manufacture, the recesses intrude considerably into the planing surfaces of the hull. In order to reduce this intrusion, plates are fixed across part of each recess after assembly of the suspension. These plates are currently glued into position, although they could be bolted. As will be seen from FIG. 1 of the above prior application, it is clear that particularly the front wheel recesses are very much open at the bottom. As a result of the openings in the bottom of the hull, there can be problems with drag on the hull when the vehicle tramps through rough water. This is particularly problematic for vehicles smaller and lighter than that shown in the prior application.
A further known solution to this problem of reducing drag on water is disclosed in U.S. Pat. No. 4,958,584, to Williamson. In this patent, a single sliding cover 18 (FIG. 5) for front and back wheel wells 42 on one side of the vehicle is powered fore and aft by a double acting hydraulic cylinder 148. This arrangement appears to be a very simple and elegant solution, but has considerable practical drawbacks.
First, the slide channels will be susceptible to damage or seizure due to ingress of sand or silt. Second, the cover runs parallel to the hull for most of its length; so any grounding or collision damage which distorts either the hull or the cover would be liable to cause the two parts to jam together, preventing protraction of the wheels and stranding the vehicle on water.
Third, the use of a single actuator to move such a large and complex sliding panel is liable to lead at the least to uneven panel movement, and at the most to complete seizure, especially as wear and play build up as the vehicle ages. Finally, a single cover as shown, which overlaps the hull between front and rear arches even when closed, would project below the hull at the front, at least, of each wheel arch, disturbing the smooth flow of water along the vehicle's planing surface. Clearly, fresh thinking is needed.
An object of the invention is, therefore, to further reduce drag on an amphibious vehicle when in water.